Light projection apparatus



A. Y. DODGE LIGHT PROJECTION APPARATUS sepms, 19a;

Filed May 2. 1930 2 Sheets-Sheet 1 Sept. 13, 1932. A. Y. DODGE 1,877,284

LIGHT PROJECTION APPARATUS Filed may 2. 193g l 2 sheets-sheet 2 of lam the parabolic reflector sends out a Patented Sept. 13,i 1932 PATENfll YDFFI ADlEL'. DODGE, OF SOUTH BEND, INDIANA LIGHT PROJECTION APPARATUS Application led May 2,

My invention relates to an im roved light projection apparatus such as mlght be suitable for head lamps for automobiles, in which a reiiector, usually of a arabolic shape, en-

. closes an electric lamp bulb. In this type power ul beam of substantially parallel rays, but allows a large proportion of light to escape as direct rays through the open front of the reflector, a large proportion of which is directed in such manner as to be wasted and positively detrimental.

One of the objects of my invention is to provide improved means for redirecting land utilizing certain of the direct rays which, in

present types of lamps, are wasted or harmful. In carr ing out this idea I provide a construction 1n which the upwardly directed rays are refracted so as to be substantially horizontal but so as to continue to diverge laterally.

I accomplish these results by attaching to the bulb a molded lens having a configuration which will give the desired result. This atals tached lens may be cemented to the bulb by means of a transparent lacquer at its lines of contact therewith, or the lens may be welded to the glass along the contact line.

Referring to the drawings, in which an emso bodiment of my invention is shown:

Figure 1 is a vertical axial section through a head lamp embodying my improvements;

Fig. 2 is a horizontal axial section substantially on the line 2-2 of Figure 1;

Fig. 3 is an enlarged vertical axial section through the' lens attachment;

Fig. 4 is a front view of the lens attachf ment Fig. 5 is an enlarged side elevation of the y 1930. Serial No. 449,108.

of the rays from the 1i ht source 8 which would otherwise escape t rough the front of the reflector in directions which would be wasteful and detrimental. This lens format1on 7 is so designed in general that the rays from the light source 8 intercepted thereby will be refracted to a general horizontal direction as shownin Figure 1 at 9, but such that their lateraldivergence will be changed very little as shown at 10 in Fig. 2. With this object in view the lens is so designed that practically every section through the lens in a horizontal plane will have its front and rear edges respectively defined by concentric circular arcs as may be seen from an inspectlon of F ig. 6, while vertical axial sections will have in general the section shown in Fig. 3, the formation of which is such that the rays of light from the light source 8 intercepted by the lens 7 will in general be refracted so as to emerge in a general horizontal direction as indicated in Figure 1 at 9. A

In order that those skilled in the art may be able to practice the invention, I have made Figs. 3, 5, 6 and 7 to scale in accordance with dimensions which I have found give satisfactor results in practice, using a certain standar lamp bulb, the frontsurface of which has in general a s herical shape having a radius of about H- with a center substantially between the upper and lower filaments of 11 and 12, respectively, of the double filament lamp 4. f The front face of the lens comprises in a general way three surfaces or zones, the lower one lying between the points 13 and 14 of Fig. 3 being formed as a surface of revolution about a vertical axis through the center 15 of Fig. 6 of an arc about the center 16 of Fig. 5 and havin a'radius 17.

The upper zone or surface rom 18 to 19 (Fig. 3) is formed in general as a surface of revolution about a horizontal axis substantially through the center 20 of Fi 7 of the arc 18--19 about the center 16 of ig. 5 and, having a radius 21 of Fig. 5. The crescentshaped intermediate zone or surface from 18 to 14 of Fig. 3 is formed in general as a surface of revolution about a Vertical axis substantially through the center 15 of Fig. 6 of the straight line 14-18 of Fig. 3, this conical surface thus generated being bounded by its intersection with the surfaces of revolution of the upper zone 18--19 and the lower zone 13-14.

The part of the lower` zone or surface below the horizontal axial plane is of considerably less extent laterally than the portion above this horizontal plane, the lower portion having an anvular magnitude of about degrees as in icated in Fig. 6, whereas the portion above the horizontal axial plane has an angular magnitude of about 120 degrees. The lateral edges of the lower portion of the lower zone are bounded by vertical planesv 22 and 23 extending through the center 15 of Fig. 6.

The rear face of the lens comprises in a general way four cylindrical zones or surfaces, the main zone comprising a cylindrical surface having a vertical axis throu h the center 15 of Fig. 6 and a radius 24 of ig. 6, the next cylindrical zone above this lower zone having a cylindrical surface also having the vertical axis extending through the center 15 and a radius 25 of Fig. 6. The next zone above has a cylindrical surface also having an axis extending through the center 15 and a radius 26. The remaining cylindrical surface has a horizontal axis extending through the center 20 of Fig. 7 and having a radius 27 of Fig. 7.

It will be seen that in general, horizontal sections through the lens will be bounded in the front and rear, respectively, by concentric circular arcs, so that there will be little if any lateral refraction of the rays so that their divergence will remain substantially unchanged as indicated in Fi s, -2 and 6. However, the dimensions given or the vertical axial sections through the lens are such that substantially all the rays intercepted by the lens will be refracted so as to emerge in substantially horizontal directions, thus preventing waste and eliminating glare. It will be appreciated that the rays which do not jx fall on the parabolic reflector 1 are now focused so that there is a minimum of ascending light rays whicharevents glare for an approaching driver an results in a great benefit for the driver of the car equipped with this lens in fog, dust or falling snow. By experiment I have found that it is very desirable that there should be some illumination above the horizontal plane. I have found that substantially the proper amount of upwardly directed light is secured by this lens due to the slightly rounded edges ofthe 1 vertical sections which do not focus the light as does the major portion of the lens. Rays which strike either the convex or concave radii in this lens are scattered, some upwardly and some downwardly.l This results in just lthe right amount of upwardly directed rays, giving an illuminationwhich is suicient for driving purposes but which is not and causes a'reduced fo screen for the driver of the car equip ed wit the lens.

While but a single embodiment of this invention is disclosed, it is to be understood that various modifications 'thereof may be apparent to those skilled in the art without departing from the s y irit and scope of this invention, and, there ore, the same is to be limited only by the scope of the prior art and the appended claims.

I claim:

1. A lens formation'for use with the bulb member of a horizontally disposed electric lamp for forwardly projecting reflectors, said formation being in general concave-convex, the convex side having one zone below the horizontal plane throu h the lamp axis and three zones above sai plane, the zone below said plane and the first zone above said plane being generated as a surface of revolution by revolving a circular arc about a vertical axis extending substantially through the light source, said circular archaving a center intermediate the light source and the circular arc, and adjacent said horizontal plane, about 45 of said arc being above said horizontal plane and 45 below said plane, the second zone above said plane having in general a crescent-shape generated by revolving a forwardly and upwardly inclined line about a vvertical axis extending substantially through the light source, the inner edge of said middle zone being the intersection of the two surfaces of revolution, the upper zone being generated as a surfaceof revolution by revolving a second circular arc about a horizontal axis extending substantially through the light source, the vertical axial section of said upper zone being a circular arc, the center of which is below and in front of the light source, the lower edge of the lower zone lying substantially in a horizontal plane and being substantially closer to the horizontal axial plane than is the upper edge of the u per zone, the sides of the lens formation elow the axial horizontal plane lying substantially in vertical planes through the light source, said vertical planes embracing between them about 60, the first zone above the horizontal axis extending laterally on both sides substantially beyond the lower zone, the concave side of said lens formation having one zone below the-horizontal axial plane and four zones above the horizontal axial plane, the zone below the axial plane and the first zone above the axial plane lying in the surface of. a first cylinder having a vertical axis extending substantially through the light source, the radius of said cylinder being substantially the radius of ahorizontal axial section of the bulb, the second zone above the horizontal axial plane lying in the surface of a second cylinder having a vertical axis extending through the light source and having a smaller radius than that of the first cylinder, the third zone above the horizontalw plane lying substantially in the surface of a third cylinder coaxial with said second cylinder and havin a smaller radius than said second cylindger and the fourth zone above the horizontal plane l ing substantially in the surface of a cylinder aving a horizontal axis extending through the light source, the upper edges of said cylinders lying substantially tangent to the surface of the bulb, the rear edge of the lens formation above the horizontal axial plane lying substantially in the surface of a plane perpendicular to the horizontal axis of the lamp and in front of the light source and ultantially tangent to the surface of the 2. A lens formation for use with the bulb member of a horizontally disposed electric lamp for forwardly projecting reflectors, said lens formation having its front face generally convex, the rear face having a portion of its surface in the form of a cylinder having its axis transverse to the horizontal plane through the axis of the bulb and having another portion of its surface in the form of a cylinder coaxial with said first cylinder but of a Vdiii'erent diameter.

V3. The combination with a horizontally disposed electric lamp having a bulb portion, of a concave-convex lens formation in front of and embracing a portion of said bulb, said lens formation having a generall convex front face and having a substantia ly c lindrical rear face portion tangent to said ulb portion along a circular arc, the axis of said cyliidrical portion being substantially ver tica 4. The combination with a horizontally disposed electric lamp having a bulb portion, of a concavo-convex lens formation in front of and embracing a portion of said bulb, said lens formation having a generally convex front face and having a substantially cylindrical rear face portion tangent to said bulb portion along a circular arc, the axis of said cylindrical portion being substantially vertical and the arc of tangency lying subtartially in the horizontal axial plane of the 5. The combination with a horizontally disposed electric lamp having a bulb ortion, of a concavo-convex lens formation 1n front of and embracin a portion of said bulb, said lens formation aving a generally convex front face and having two substantially ylindrical rear face portions of different iameters, both surfaces being tangent to said bulb portion along circular arcs, respectively, said cylindrical surfaces being coaxial.

7. `The combination with a horizontally disposed electric lamp having a bulb portion, of a concavo-convex lens formation 1n front said lens formation having a generally convex front face and having two substantially I cylindrical rear face portions of different diameters, both surfaces being tangent to said bulb portion along circular arcs, res ectively, the axis of both cylindrical sur aces beingl substantially vertical.

8. The combination with a horizontally disposed electric lamp having a bulb portion, of a concavo-convex lens formation in front of and embracing a portion of said bulb, said lens formation having a generally convex front face and having two substantially lcylindrical rear face portions of different diameters, both surfaces being tangent to said bulb portion along circular arcs, respectively, the axis of both cylindrical surfaces being substantially vertical and one of the arcs of tangencg ling in the horizontal axial plane 4of the ul In witness whereof, I have hereunto subscribed my name. v

A DIEL Y. DODGE.

front face and having two substantially c lindrical rear face portions of different iameters, both surfaces being tangent to said bulb portion along circular arcs, respectively.

6. The combination with a horizontally disposed electric lamp having a bulb portion, of a concavo-convex lens formation in front of and embracin a portion of said bulb, said lens formation avlng a generally convex 

